Embossing devices of the type mentioned above are known in a great variety from prior art. For example, EP 1 096 069 A2 discloses such an embossing device for producing a multi-layer absorbent paper product with an embossed pattern, wherein each layer is unwound from an unwinding device and supplied to a roller couple consisting of a squeezer and an embossing roller. The respective layer webs are embossed, one of the webs is furnished with glue and, in order to form a so-called “nested” structure, is then run through a nip arranged between two embossing rollers of the roller couples, and the layers are firmly bonded to one another by a downstream joining roller.
There is now an increased need for planar products with two or more layers, particularly those made of tissue or tissue-like materials, such as toilet paper, facial tissue, kitchen towels and the like that bear decorative patterns. It is desirable in this case that the decorative patterns appear very striking and sharp, and that the planar product optionally be given an additional visual effect by means of color.
In the sense of the present invention, tissue is understood to be a product conforming to DIN 6730. According to the latter, tissue is a product that consists entirely or predominantly of cellulose fibers, with a fine and soft creping, which is creped with a dry content of more than 90% in closed formation in the paper machine, consists of one or more layers, is particularly absorptive, has a specific surface weight of less than 5 g/m2 before creping, and a wet elongation of the crepe of greater than 5%.
In the sense of the present invention, tissue-like material is understood to mean a material which, unlike tissue material, is produced by changes in the dry process. According to DIN 6730, tissue-like material is a product predominantly made of cellulose fibers, with large creping and open formation, which is creped dry in the paper machine and consists of one or more layers, wherein the basis weight of a ply before the creping is less than 25 g/m2 and the wet crepe expansion of a ply after creping is greater than 24%. The material can also be produced from old paper.
EP 1 609 589 A2 discloses an imprinted and embossed facial tissue that can be produced with a device consisting of at least two roller couples, comprising an embossing roller, these embossing rollers having embossing points of different heights. A ply is first provided with a micro-embossing when passed through a first roller couple, and subsequently with a motif embossing when passed through a second roller couple.
U.S. Pat. No. 6,106,928 discloses a device in which plies are conducted from an unwinder to a first and second roller couple, wherein embossing rollers comprised by these roller couples have embossing points of a first height and embossing points of a second height and thus embossing points distributed over their entire embossing surface.
It is therefore the problem of the present invention under consideration to provide an embossing device by means of which high-quality planar products, provided with decorative patterns, can be easily produced.